Field of the Invention
The present invention relates to a luminance control device and a luminance control method for controlling luminance of a light emitting member.
Description of the Related Art
Generally, a light-emitting element such as an LED element or an organic EL element may be controlled with fade-in processing or fade-out processing so that the luminance gradually changes. When the luminance of the light emitting element is controlled with pulse width modulation control, duty ratio of the pulse current or the pulse voltage for driving the light emitting element is changed in each of a plurality of unit periods within the luminance transition period. At this time, when the difference (variation width) of the reference duty ratio in the adjacent unit period is large, discontinuous changes tend to be visually recognized by the user, and there is a possibility of giving a sense of discomfort. On the other hand, in order to reduce the range of change in the reference duty ratio, it is necessary to divide the luminance transition period into a large number of unit periods, and to store the reference duty ratio every unit period, increasing the amount of information to be stored.
Therefore, disclosed is a luminance control device integrating the reference duty ratio every time a period shorter than the unit period elapses with the unit luminance variation width finer than the predetermined luminance variation width which is the difference between the reference duty ratios in the adjacent unit period (for example, refer to Patent Document 1). Such a luminance control device tries to alleviate the sense of discomfort given to the user by reducing the variation width of the luminance of the light-emitting element. Also, the reference duty ratio and the unit luminance variation range in each unit period may be stored, suppressing an increase in the amount of information.